Nanoindentation is a method to quantitatively measure a sample's mechanical properties, such as elastic modulus and hardness, for example, using a small force and a high resolution displacement sensor. Typically, a force employed in nanoindentation is less than 10 mN, with a typical displacement range being smaller than 10 μm, and with a noise level typically being better than 1 nm rms. In nanoindentation, a nanoindenter capable of determining the loading force and displacement is used. The force and displacement data are used to determine a sample's mechanical properties. In some examples, for sample property estimation a nanoindenter is integrated with a characterized tip which has known geometry and known mechanical properties.
One of the emerging nanoindentation applications is quantitative transmission electron microscopy (TEM) in-situ mechanical testing. This testing method enables monitoring of the deformation of a sample in real time while measuring the quantitative mechanical data. Coupling a nanomechanical system with TEM imaging allows researchers to determine certain material parameters such as variations in chemical composition or the presence of pre-existing defects in the specimen. In addition to imaging, selected-area diffraction can be used to determine sample orientation and loading direction. Moreover, with in-situ mechanical testing, the deformation can be viewed in real-time rather than “post mortem”. Performing TEM in-situ nanomechanical testing can provide unambiguous differentiation between the many possible causes of force or displacement transients which may include dislocation bursts, phase transformations, shear banding or fracture onset while minimizing the effects of elastic recovery of the material surrounding the indentation.
Nanomechanical testing at elevated temperature is an important part of material characterization for materials having phase changes or variant mechanical properties as the temperature increases. Some of the applications of the high temperature nanomechanical test are glass transition temperature identification of polymeric and rubber materials, phase transformations of low temperature metals and shape memory alloys, study of biological samples at body temperature, simulated and accelerated thermal aging studies, accelerated material creep studies, and time-temperature-superposition curve plotting of polymers.